The invention discloses an anti-blocking device for an oil well pump. The anti-blocking device for the oil well pump comprises a lower connector which is connected with an oil well tube and an external connecting tube which is in thread connection with the lower connector; a sealing ring is arranged between the lower connector and the external connecting tube; the lower end of the lower connector inside the external connecting tube is in thread connection with an internal connecting tube I; a valve base is arranged between the internal connecting tube II and the lower connector; an internal connecting tube II is welded to the rear end of the internal connecting tube I; a sand prevention hole is formed in the internal connecting tube II; a sand setting chamber is arranged between the internal connecting tube II and the external connecting tube; a conical cap is welded to the rear end of the internal connecting tube II; the lower connector, the external connecting tube, the internal connecting tube I and the internal connecting tube II are each internally provided with a channel; a steel ball is arranged inside the internal connecting tube I. The anti-blocking device for the oil well pump has the advantages that the sand setting chamber is formed, sand grins enter the sand prevention hole after buffering, blocking is avoided, the sand grains are effectively filtered and avoided from entering the oil well pump, and influences to the oil well pump from the sand grains are effectively eliminated.